Fuels and lubricants containing inclusion compounds



United States Patent 3,314,884 FUELS AND LUBRICANTS CONTAINING INCLUSION COMPOUNDS Richard E. Cover, Woodhaven, N.Y., assignor to Mobil Oil Corporation, a corporation of New York No Drawing. Filed Jan. 2, 1964, Ser. No. 335,422 20 Claims. (Cl. 252) The present invention relates to organic compositions such as lubricants and fuels and to an improved type of additive for these compositions.

As is known in the art, a variety of chemical compounds are normally added to fuels and to lubricating compositions in order to improve their characteristics in various respects. Thus, for example, additives are used to improve the oxidation stability, anti-wear and extreme pressure characteristics, pour point, viscosity index, etc. of lubricants, as well as to improve the combustion properties, rust-resistance, oxidation stability and other properties of petroleum-derived fuels. Normally, these additives in their active state are admixed with the particular composition sometime prior to the time of ultimate use. This is often a significant disadvantage since it means that the additive may precipitate out or may be subject to degradation and deterioration prior to the complete use of the fuel or lubricant composition. As a result the effectiveness of the additive is frequently lessened or eliminated during the period when it is most needed. It would therefore be desirable to provide a means whereby the effectiveness of the additives could be regulated and controlled.

In accordance with the present invention, the above mentioned disadvantages are largely overcome by employing the fuel or lubricant additives in the form of certain types of inclusion compounds wherein the additive is contained within the frame work of another compound.

It is therefore an object of the present invention to provide improved fuel and lubricating compositions possessing a superior type of chemical additive. A further object is to provide improved additives for fuel and lubricant compositions. Another object is to furnish a means for controlling additive release in such compositions. Further objects of the invention and the advantages thereof will become apparent hereinafter.

In general, inclusion compounds of the present invention are formed by combining the chemical additive, e.g., antioxidant, E.P. agent, combustion improver etc. which is herein referred to as the guest compound with a selected compound, i.e., the host, which because of its stereochemical properties and/ or polarity, has the ability to spatially enclose the guest compound. More particularly, the additives of the present invention may be in the form of either of two general types of inclusion compounds which are classified according to the nature of the host or enclosing compound. These inclusion compounds are either (1) polymolecular or lattice inclusion compounds or (2) monomolecular inclusion compounds.

The polynuclear or lattice inclusion type are inclusion compounds composed of polymolecular host structures where the lattice is built up from smaller single molecules. The host structure of such compounds may contain either channel-like spaces or cages (clathrates). Some examples of inclusion compounds of this type are those wherein the host compound is urea, thiourea, chloeic acids, i.e., desoxycholic and apochlolic acid, hydroquinone, phenol, triortho-thymotides etc.

The monomolecular inclusion compounds are so termed because it is thought that only one molecule is host to the guest molecule. The host compound will therefore be large and will generally possess spaces in its center as in the case of larger ring molecules. The cyclodex- 3,314,834. Patented Apr. 18, 1967 trins of either the 0:, B or 'y type are typical monomolecular host compounds.

The inclusion compounds of the invention are, as far as is known, addition compounds wherein the guest compound, i.e., chemical additive, is geometrically entrapped within the cavities of the host. Thus, the selection of particular guest compounds is limited by geometrical rather than chemical considerations. In general, any additive compound possessing a molecular geometry, i.e., a size and shape, which both allows entrance into the available space of the host compound and prevents ready escape through the openings in the framework of the host, may be formed into an inclusion compound and employed according to the present invention. Some examples of suitable additives which may be used as guest compounds include fatty acids, such as those containing 1 to about 18 carbons; carboxylic acid esters including aliphatic, aromatic or mixed esters; ketones such as acetone, methyl ethyl ketone etc.; ethers; long chain or fatty alcohols; phenols; halogenated organic compounds including halogenated paraffins, halogenated carboxylic acids; organic sulfur compounds; primary, secondary and tertiary amines etc.

According to a particular aspect of the invention, it has been found that gaseous materials such as hydrogen chloride, ammonia, chlorine, bromine and sulfur dioxide, which because of their physical state have not been especially useful as additives, maybe used as additives in the form of inclusion compounds. Phenol, hydroquinone and the cyclodextrins are particularly suitable as host compounds with these gases.

The procedure for preparing the inclusion compounds will vary depending on a number of factors especially the nature of the host and guest compounds. A convenient method is use of a mutual solvent to bring the two components together, or in the case of gaseous additives the guest compound may be bubbled through a suitable solution, dispersion etc. of the host compound. Depending on the nature of the other ingredients present, the inclusion of the invention may be prepared. in situ, i.e., while present in the fuel or lubricant compositions. The preparation of inclusion compounds used according to the present invention is well known in the art. Particular details regarding these compounds and their preparation are described in Clathrate Inclusion Compound, M. Hagan, Reinhold Publishing Company, 1962, and in "Einschlussverbindungen, F. Cramer, Springer Verlag, Berlin, 1954.

Since the guest and host compounds are normally not chemically bonded together, they can be readily freed from the inclusion structure and made available for chemical reaction. In general, any mechanism which destroys the framework of inclusion compound or supplies sufficient energy will set free the included additive. Thus, in order to free the guest from the structure it is only necessary to melt, dissolve or otherwise disintegrate the structure of the host compound. It should be noted, however, that since the guest molecule is completely enclosed by the host compound, the guest or chemical additive, is substantially prevented from reacting with the particular environment around the inclusion compound until the additive is released from the surrounding host compound.

The use of the included additives of the present invention offers several distinct advantages over the practice of employing the additives in their active state. For example:

(l) The degradation of the additive during storage and prior to use is minimized.

(2) It is possible to incorporate additional amounts or reserve amounts of additives above the present levels without affecting the properties of the fuel or lubricating compositions since the reserve amounts of additives are present in the inclusion compound and not capable of substantial chemical reaction with other components.

4 automatically applying pressure between the rubbing surfaces at a predetermined rate and measuring the torque developed. The test sample is placed in a test cup which is positioned so that the V blocks and shaft are partially (3) The use of inclusion compounds makes possible the 5 submerged. The pressure between the rubbing surfaces is use of additives which heretofore, because of their suscepincreased until seizure occurs. The OK load is the tibility to oxidative or bacteriological attack during highest reading obtained before seizure. The higher the storage, could not be employed. For example, gases and OK load the more desirable is the ER characteristics of oxidation-sensitive materials may be formed into incluthe composition. sion compounds and added to fuel or lubricating composi- 1O Four-ball test tions.

(4) In the case where the particular host compound According to the four-ball test, the samples to be per se has a useful additive eifect it is possible to achieve tested are placed between three fixed and one rotating a sequential additive action when the inclusion comsteel balls of a standard four-ball machine. The steel pound is decomposed since at this point another addiballs are rigidly clamped in contact with each other and tive i.e., the guest compound or compounds, then acts on pressed by means of a loading lever against the rotating the composition. fourth ball. The rotational speed of the top ball is con- The use of the additives in the form of inclusion comstant at approximately 1735 rpm. The BF. characterispounds is particularly advantageous in lubricating comtics of the sample is indicated by the scale reading at positions. For example, while the bulk temperatures of which welding first takes place. the lubricating oils are generally relativel low, i.e., below 200 F., the oil temperatures become ap preciably higher Tappmg test at surfaces needing lubrication such as at bearing or wear In the measurement of pp g efficlehey of an 011, a surfaces. It is precisely at these wear surfaces that the series of hol s are y accurately drilled ill a test metal, need for the chemical additive is usually the greatest. By namely SAE 1020 hot rolled Steel These holes f employing included additives in accordance with the pres- Sequently pp With a Series Of taps, 111 a drlll Press ent invention it is possible to achieve the controlled req pp With a table, Whleh is e to rotate about e lease of the additive at the point of maximum need for center, being mounted 011 hall hearlllgsz A fl arm 13 these additives since the temperatures existing at the attached to this floating table and thls arm t Wear surfaces during use will generally be sufficient to detuates a Spring Scale 50 that the aetufll torque durlhg P- compose the inclusion compound and release the addi- P With the Oil being evaluated 18 measured directlytive. The same taps used in evaluating the test oil are employed The inclusion compounds may be admixed with the in PfP With Standard reference which has fuels and lubricant compositions using any suitable hitraflly been asslghed an e ey Of 100 Percent The procedure to form either a solution, dispersion or susaverage torque the t 011 eohflpafed to that Of pension. Various procedures for achieving this admixture the Standard h a relatlve'efiicleney 1S ealculated on a will be apparent totho'se in the art percentage basis. The tapping efficiency is calculated as The amount of inclusion compound used in the comfollows: positions will vary depending on factors such as the type of additive, its proportions in the inclusion compound 40 Torque Wlth stanfiard refefence 100% etc. As a practical matter, the fuels or lubricating corn- Torque Wlth test 011 positions generally contain .less than 9 by Weight of The higher the tapping efficiency, the higher is the film the inclusion compound, while amounts in the range from b t00001'7 t b r207 b iht 't b1 Strengthoflubncam' a on on o y g are Sm a The results of the tests are shown in the following The invention Wlll be further illustrated by reference table to the following Specific embodlments' The hydrogen chloride-hydroquinone inclusion com- A cuttmzgpll and a grease were i t the pound employed was crystallized from a saturated soluacidltlves ac.cordmg to the present lnventl9n' h tion of hydroquinone in ethyl ether which had been satucuttlng 011 was sub ected to the Falexand Tapping tests, rated with hydrogen Chloride at C While the hydro Whlle the grease was evahflated. by the four'ban test gen sulfide-hydroquinone inclusion compound was crystal- These tefts are rec9g.mzed m.the art as standard tests lized from a saturated aqueous solution of hydroquinone for evaluating Compositions of this type which had been saturated with hydrogen sulfide at 30 C.

Falex test The sulfur dioxide hydroquinone inclusion compound was formed by passing a steady stream of sulfur dioxide In the Falex test the lubricants to be tested are inthrough a saturated aqueous solution of hydroquinone at troduced into a Falex lubricant tester which is a device room temperature and recovering the slowly crystallizing wherein a shaft is rotated between two V-shaped bearing product. The included additives were admixed with the blocks, with provision for varying the rubbing speed, oil compositions, thoroughly stirred and then tested.

TABLE.TEST RESULTS Lubricating Falex Test Tapping Four Ball Composition Additive 1 OK Load Eflicicncy Weld (kg) (lbs.) (Percent) Cutting oil 2 1,000 Cutting oil plus Hydroquinone 1,250 Do HCl-hydroquinonenn 2,000 Ins-hydroquinone. 1, 250 SO -hydroquinonm 2, 250

Hydroquinone. HCl-hydroquinon Tbs-hydroquinone.

SOz-llYdIOQUlIlOHQ.

1 Concentration of additive was 8.1% by wt. for the cutting oil, 7% by wt. for the grease by wt. added sulfur).

gravity of 21, and min. flash point of 370 F., containing 6% by wt. Cal-O-Sil (colloidal silica).

It will be seen from the above that the Falex test data indicates that the inclusion compounds produced a significant improvement in the BF. properties of the oil, while the tapping efficiency tests show that the addition of the inclusion compounds results in a significant improvement in film strength properties. Similarly, the four-ball test results indicate that improved E.P. properties are imparted to the grease by the use of these hydroquinone inclusion compounds.

Although the above embodiments are limited to certain inclusion compounds, it should be noted that these specific embodiments are merely exemplary and the present invention is not limited thereto.

The present invention encompasses the use in the form of inclusion compounds of any chemical additive normally used in conjunction with fuels or lubricants to improve the characteristics thereof including but not limited to combustion improvers, ignition control agents, deposit modifiers, oxidation inhibitors, metal deactivators, antiicing agents, anti-corrosion agents, sludge depressants, de tergents, pour depressants, VI improvers, defoaming agents, color stabilizers, odor maskants etc.

Depending on the size and shape of these guest additives any host compound selected from the two general types hereinabove described may be employed.

The compounds of the present invention wherein the additive is in the form of an inclusion compound may be employed with various types of lubricants and hydrocarbon fuels. Thus, lubricants comprising both petroleum and synthetic oils, e.g., synthetic hydrocarbon and synthetic ester, such as greases and oils used with internal combustion engines, turbine engines, machinery, including hydraulic fluids, gear oils etc. may be improved by the use of the inclusion compounds of the present invention. The hydrocarbon fuels include gasoline, diesel fuel, kerosine, industrial and home fuel oils, jet fuels etc.

The lubricant and fuel compositions of this invention may, of course, also contain effective quantities of other ingredients normally used in such compositions and designed to improve the characteristics of these compositions in other respects. For example it may be desirable to employ suitable dispersing agents of either the ionic or non-ionic type or other additives which are not employed in the form of inclusion compounds.

Many variations and modifications may, of course, be made without departing from the scope and spirit of the present invention.

Having described the invention, what it is desired to secure and claim by Letters Patent is:

1. An organic composition selected from the group consisting of lubricants and normally liquid hydrocarbon fuels containing an amount effective to enhance the useful characteristics of said composition of a chemical additive in the form of an inclusion compound wherein said additive is enclosed within the cavities of a host compound having a structure selected from the group consisting of a lattice structure and a mono-molecular structure, the molecule of the said additive being smaller than that of the said host.

2. A lubricating composition according to claim 1.

3. A normally liquid hydrocarbon fuel composition according to claim 1.

4. The composition of claim 1 wherein said host compound is a polymolecular compound having a lattice structure.

5. The composition of claim 1 wherein said host compound is a monomolecular compound having a space within the center of the molecule capable of enclosing a smaller molecule of said additive.

6. The composition of claim 1 wherein said host compound is hydroquinone.

7. The composition of claim 1 wherein said host compound is a flavan.

8. The composition of claim 1 wherein said host compound is a tri-ortho-thymotide.

9. The composition of claim 1 wherein said host compound is a cyclodextrin.

10. The composition of claim 1 wherein said host compound is urea.

11. The composition of claim 1 wherein said host compound is thiourea.

12. The composition of claim 1 wherein said host compound is phenol.

13. The composition of claim 1 wherein said host compound is choleic acid.

14. The composition of claim 1 wherein said chemical additive is a gas.

15. An organic composition selected from the group consisting of lubricants and normally liquid hydrocarbon fuels containing from about 0.0001% to about 20% by weight of said composition of an additive in the form of a hydrogen chloride-hydroquinone inclusion compound.

16. An organic composition selected from the group consisting of lubricants and normally liquid hydrocarbon fuels containing from about 0.0001% to about 20% by weight of said composition of an additive in the form of a hydrogen sulfide-hydroquinone inclusion compound.

'17. An organic composition selected from the group consisting of lubricants and normally liquid hydrocarbon fuels containing from about 0.0001% to about 20% by weight of said composition of an additive in the form of a sulfur dioxide-hydroquinone inclusion compound.

18. An organic composition selected from the group consisting of lubricants and normally liquid hydrocarbon fuels containing an effective amount suflicient to enhance the useful characteristics of said composition of an inclusion compound comprising a guest compound enclosed within the cavities of a host compound and wherein both said guest compound and said host compound are chemical additives, said host compound having a structure selected from the group consisting of a lattice structure and a monomolecular structure, the molecule of the said additive being smaller than that of the said host.

19. A method of lubricating moving metal surfaces comprising the steps of (1) applying to the said surfaces a lubricant composition containing an amount of a chemical additive sufficient to enhance the lubricating properties of said composition, said additive being in the form of an inclusion compound wherein the additive is enclosed within the cavities of a host compound selected from the group consisting of lattice-molecular compounds and spatial-monomolecular compounds; and (2) subjecting said lubricant composition, while in use, to conditions whereby the said host compound is deteriorated, thereby releasing said enclosed additive into the said composition.

20. A method of stabilizing a fuel which comprises adding to a normally liquid hydrocarbon fuel composition, capable of being compounded with chemical additives, an additive in an amount sufficient to improve the storage and combustion characteristics of said fuel, said additive being in the form of an inclusion compound wherein the additive is enclosed within the cavities of a host compound selected from the group consisting of lattice-molecular compounds and spatial-monomolecular compounds; and (2) subjecting said fuel composition to conditions whereby said host compound is deteriorated thereby releasing said enclosed additive into the said composition.

References Cited by the Examiner UNITED STATES PATENTS 1,319,129 10/1919 Wells et a1. 252--56 1,748,507 2/1930 Brooks 4452 1,761,810 6/1930 Bjerregaard 44-78 2,008,680 7/1935 Carlisle et al. 25254 X 2,023,110 12/1935 Wilson 44--78 X 2,209,464 7/1940 Loane et al 252--47 (Other references on following page) 7 UNITED STATES PATENTS 10/1945 Lowry 44--78 X 2/1949 Fischer 4478 X 9/1960 Coit et a1. 5/1961 Binning 4 1-70 5 11/1961 Eckert et a1 4470 X 10/1962 Schlicht et a1 252-33 X 8 OTHER REFERENCES Hagan: Clathrate Inclusion Compounds, Reinhold Publishing Corp. (1962).

DANIEL E. WYMAN, Primary Examiner.

P. P. GARVIN, Assistant Examiner. 

1. AN ORGANIC COMPOSITION SELECTED FROM THE GROUP CONSISTING OF LUBRICANTS AND NORMALLY LIQUID HYDROCARBON FUELS CONTAINIGN AN AMOUNT EFFECTIVE TO ENHANCE THE USEFUL CHARACTERISTICS OF SAID COMPOSTION OF A CHEMICAL ADDITIVE IN THE FORM OF AN INCLUSION COMPOUND WHEREIN SAID ADDITIVE IS ENCLOSED WITHIN THE CAVITIES OF A HOST COMPOUND HAVING A STRUCTURE SELECTED FROM THE GROUP CONSISTING OF A LATTICE STRUCTURE AND A MONO-MOLECULAR STRUCTURE, THE MOLECULE OF THE SAID ADDITIVE BEING SMALLER THAN THAT OF THE SAID HOST. 